Modding the Location identifiers in default FS9 AFCADs

HelloI am doing a small project involving updating a couple of default AFCADs in FS9. I noticed that in a couple of the AFCADs, the location identifiers (country, city, etc) are inaccurate or could be better described. I was wondering, if I changed these fields in my modded versions of AFCAD will it cause any problems (i.e. duplicate airports showing up in the airport selection menu) because they are different from the stock AFCAD's properties? The ICAO will not be changing, only the region/country identifier. Or does FS9 sort AFCADs based on ICAO only, and if it finds a 3rd party AFCAD with the same ICAO, all data from the original file is superceded?Ruahrc